Supplementary data for the paper ‘Stopping by looking: A driver-pedestrian interaction study in a coupled simulator using head-mounted displays with eye-tracking'

Automated vehicles (AVs) can perform low-level control tasks but are not always capable of proper decision-making. This paper presents a concept of eye-based maneuver control for AV-pedestrian interaction. Previously, it was unknown whether the AV should conduct a stopping maneuver when the driver looks at the pedestrian or looks away from the pedestrian. A two-agent experiment was conducted using two head-mounted displays with integrated eye-tracking. Seventeen pairs of participants (pedestrian and driver) each interacted in a road crossing scenario. The pedestrians’ task was to hold a button when they felt safe to cross the road, and the drivers’ task was to direct their gaze according to instructions. Participants completed three 16-trial blocks: (1) Baseline, in which the AV was pre-programmed to yield or not yield, (2) Look to Yield (LTY) in which the AV yielded when the driver looked at the pedestrian, and (3) Look Away to Yield (LATY) in which the AV yielded when the driver did not look at the pedestrian. The driver’s eye movements in the LTY and LATY conditions were visualized using a virtual light beam. A performance score was computed based on whether the pedestrian held the button when the AV yielded and released the button when the AV did not yield. Furthermore, the pedestrians’ and drivers’ acceptance of the mappings was measured through a questionnaire. The results showed that the LTY and LATY mappings yielded better crossing performance than Baseline. Furthermore, the LTY condition was best accepted by drivers and pedestrians. Eye-tracking analyses indicated that the LTY and LATY mappings attracted the pedestrian’s attention, but pedestrians adequately distributed their attention between the AV and a second vehicle approaching from the other direction. In conclusion, LTY control may be a promising means of AV control at intersections before full automation is technologically feasible.

自动驾驶汽车（Automated Vehicles，AVs）可完成低级控制任务，但往往无法做出恰当决策。本文提出了一种面向自动驾驶汽车与行人交互的基于视线的操作控制概念。此前，尚不清楚当驾驶员看向行人或是移开视线时，自动驾驶汽车是否应当执行停车操作。本研究采用两台集成眼动追踪功能的头戴式显示器开展了双主体实验。共17组参与者（行人与驾驶员配对），每组均在一个道路横穿场景中进行交互。行人的任务为：在认为横穿马路安全时按住按钮；驾驶员的任务则为按照指令调整视线方向。参与者共完成三个含16次试次的实验单元：(1) 基线组（Baseline）：自动驾驶汽车预先编程为礼让或不礼让行人；(2) 视线礼让组（Look to Yield，LTY）：当驾驶员看向行人时，自动驾驶汽车执行礼让操作；(3) 移开视线礼让组（Look Away to Yield，LATY）：当驾驶员未看向行人时，自动驾驶汽车执行礼让操作。在LTY与LATY条件下，驾驶员的眼动轨迹通过虚拟光束进行可视化展示。基于行人在自动驾驶汽车礼让时按住按钮、未礼让时松开按钮的表现计算绩效得分。此外，通过问卷调研评估行人与驾驶员对各类映射规则的接受度。研究结果表明，LTY与LATY映射规则的横穿表现均优于基线组。此外，LTY条件最受驾驶员与行人的认可。眼动追踪分析显示，LTY与LATY映射规则能够吸引行人的注意力，但行人可将注意力合理分配至自动驾驶汽车与另一辆从对向驶来的车辆之间。综上，在全自动化技术落地普及之前，LTY控制方式可作为交叉口自动驾驶汽车控制的一种极具前景的方案。